When the government does not protect the people from crime, or worse, takes the side of the criminals against the people, vigilantism results.

Vigilantism always begins peacefully, with the petition to government to stop crime, which is ignored. Such a government sees the vigilante movement as a bigger threat to them than the criminals, so tries to stop it. Soon it turns to threats and even violence against the vigilante movement, tries to arrest its leaders, and publicly vilifies it.

The criminals join in as well, attacking the leaders and other members. Only then, finally, do the vigilantes have enough. But all they still want to do is to just drive the criminals out. Unless the criminals resist expulsion, which is when the vigilantes finally become violent.

This is all a natural progression that happens on its own, and can be stopped simply by government doing its job. But that almost never happens.

There's a general law applicable wherever people get together, and that is that if the folks who pretend their are the authorities and law givers won't protect them or require adherence to the law by the lawbreakers, the people will go to somebody else ~ might be a mobster, a neighborhood gang, a community association, an ad hoc people's militia, and so on, maybe even for help from a nearby country.

This usually results in attempt to overthrow the regime. Sometimes that works and sometimes it doesn't.

Sweden's government has only a small chance to take care of the problem now without somebody else selling the common sense idea that it would be good to get rid of the government.